DigiTech GNX Series: Using the Expression Pedal
This is a continuation of the DigiTech GNX Series: Expression Assignments article.
Expression pedal assignments are commonly used by musicians using electronic means. Generally, an expression pedal for a guitar effect is similar to a continuous controller on a MIDI instrument (such as a keyboard). Potential uses for continuous midi controllers are pitch bend or modulation; guitar effects are usually more along the lines of volume or wah. The idea is that a certain parameter, such as volume level, is assigned to a number – for instance, the GNX volume pedal can have any value between 0 and 99 – and then controlled in real-time, much like you might do with a volume fader or pot.
The possibilities on the GNX units are actually quite impressive: you can assign most parameters – amp, effects, etc – to be controlled using the expression pedal. Moreover, you can create “multi-dimensional” effects by assigning multiple parameters (up to three at a time) to be controlled with the expression pedal.
The basics of these assignments are the same as for the controller footswitches. Even if you are a GNX3000 user (without assignable controller footswitches) you should review the previous section to make sure that you have a grasp on how to assign these parameters. One major difference is that, for any parameter that has a range (i.e. not an ON/OFF parameter), the expression pedal will travel through the entire range, allowing "continuous control" of the parameter(s). Below I’m going to go through a few examples of what the expression pedal can do for you.
1. Volume boost for leads
You can assign either the pre-modulation or the post-modulation volume to the expression pedal. To do this, simply set the EXP PDL 1 parameter to either VOL PRE or VOL POST – most factory patches are already saved with this assignment.
The difference for a “volume boost” control is that your MIN value (i.e. when the expression pedal is all the way down) will be your normal level – choose a reasonable value such as 75. Your MAX value is going to be slightly higher; try 99 for the purposes of this example.
2. Assigning additional expression pedal parameter
Let’s say that you’re happy with the Volume Boost of your expression pedal, but something is missing. You want to get a lead sound that is up front and full-bodied. To achieve this, we will do two things: (1) lower the reverb level, and (2) increase the delay feedback. Obviously, for this to be effective, you’ll need to have both effects turned on prior to using the expression pedal.
Using the preset from example 1, make the following additional assignments:
• EXP PDL 2 = RVBLEVEL; MIN=15; MAX=3
• EXP PDL 3 = DLYFBACK; MIN=5; MAX=10
Once again, notice that here we are disregarding the “min/max” nomenclature of the expression pedal’s range of motion. In other words, the MIN setting for the reverb level setting is higher than the MAX setting for the same parameter – this means that as the pedal is going towards its full TOE DOWN position, the reverb level will decrease. At the same time, the volume and the delay feedback settings will increase. Reducing reverb will make your lead sound like it’s “up front”; increasing delay feedback will give it an additional degree of fullness. With these settings, once your expression pedal is all the way down (MAX position), you can also engage the modulation effect (assuming it’s suitable for a lead sound, such as chorus) and/or the stompbox for more gain and/or volume.
Caveats/other tips:
• When increasing delay feedback, it is a good idea to turn on the ducking delay – this way the delayed signal won’t get in the way of new notes you play. This is particularly important with higher feedback settings. One expression pedal setting you might choose to use in conjunction with delay feedback is “ducker attenuation” – as it increases, the amount by which new signal reduces delayed signal increases. Experiment!
• If you do not wish to change the ambient effect settings with the expression pedal, you may instead choose to assign the Stompbox On/Off and the Modulation On/Off parameter to EXP PDL 2 and 3. The assigned parameter will toggle on/off as the pedal passes the midpoint of its motion range.
3. Using the Whammy Pedal
Ah, the legendary Digitech Whammy – a tool of destruction used by many fine musicians, such as Steve Vai, Joe Satriani, Jennifer Batten, and many others. All GNX units include a full-featured monophonic Whammy, with all the same settings as the standalone pedal available.
To use the Whammy Pedal, you have to do two things: (1) turn on the IPS section – 3rd row of the matrix – and select WHAMMY as type; and (2) assign the WHAM PDL parameter to one of the expression pedal controllers. For purposes of demonstration, set the shift amount to 1 OCT UP; use EXP PDL MIN=0 and EXP PDL MAX=99. When you save your patch, be sure that the expression pedal is in the TOE UP position (this will ensure that when you switch to the patch, it’ll be on pitch).
Notice also that you can use this assignment in reverse, just like we did earlier with reverb level. In other words, try assigning the EXP PDL 1=WHAM PDL; MIN=99; and MAX=0. If you do this, save the patch with expression pedal in full TOE DOWN position – again, to make sure your pitch is unchanged when you first engage the preset. The main advantage of doing this vs. the other way is if you intend to use the Wah pedal – more on this later.
4. Stereo effects
One cool trick I learned early on with my GNX3 is the pan settings for delay, reverb, and modulation. Each of these effects can be panned through the full radius of the stereo field. To make this work, you must be running your GNX in a stereo mode (either STEREOAL or STEREOFX). Also, any module for which you adjust the panning should be turned ON for this to work (remember, you can also add these parameters as expression pedal assignments).
To get started with this, first make the following assignments:
• EXP PDL 1=MOD BAL; MIN=0; MAX=+99
• EXP PDL 2=DLY BAL; MIN=-30; MAX=+65
• EXP PDL 3=RVB BAL; MIN=-99; MAX=-15
This will allow you to do some cool tricks while playing live: imagine a clean signal with light chorus and reverb, and a MONO-type delay. Make sure that chorus, delay, and reverb are turned on. Now you can play a slow chordy part, and pan the modulations. Just be sure, especially in larger live settings, that your effect settings are not overwhelming: be reasonable with settings such as modulation mix, reverb level, and delay level/feedback. Pre-delay settings should also be used in moderation. Using too much of any of these will muddy up your signal, especially on distorted patch settings.
5. Wah pedal
The GNX units allow you to use a Wah pedal separate from all the other expression pedal parameters. There is a dedicated switch that is assigned to Wah On/Off parameter, located right below the top of the expression pedal – to toggle this setting, simply apply additional pressure in the TOE DOWN pedal position. On earlier GNX units (GNX4 and before), you may have to adjust your V-Switch sensitivity to make this work. If you’re having difficulty with this, perform the Expression Pedal calibration procedure outlined in your manual.
There are three types of Wah available on the GNX units: a classic “Crybaby” emulation, a more modern “Boutique” type, and a full-range filter sweep. Each of these will yield different results, and depending on your other patch setting (compression, stompbox, amp), each may work better than the others in any given situation.
However, you are not limited to the three pre-defined ranges of the Wah types. In the Expression Assignment matrix row (last one), WAH PDL MIN and MAX parameters can be adjusted. Suppose the CRY wah type is insufficient – it just doesn’t honk like you want it to. But, the BOUTIQUE is just too wide, and creates artifacts/buzzy tones at the top/bottom end of its range. No problem – set the Wah Type to BOUTIQUE, and adjust the MIN and MAX values to achieve a more narrow range.
The “center” frequency of the Wah (called the Q on some standalone wah pedals) can likewise be tweaked using the min/max settings. For instance, setting the range to MIN=10 and MAX=90 keeps the Q in the middle; if you offset it by increasing just the MIN or just the MAX, you’ll get a different Q. An example would be a setting of MIN=20 and MAX=90, yielding a Q of 55. Experiment with all three wah types by adjusting their ranges – you’ll be surprised at how versatile this effect really is.
Alternately, you can use the Wah Pedal parameter assigned to any of the EXP PDL controllers. For this to work, the Wah module must be turned ON (first row of the matrix). The min/max assignment will work the same way, but the added advantage is that you can add up to two more parameters for even greater expressiveness.
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